Rule of twelfths 1

There are two methods of calculating the tidal height.
The first uses the tide tables, which is a very accurate method, and the second uses the
“Rule of Twelfths”, which is not so accurate and should be used with caution!
To use the “Rule of Twelfths,” we assume that the tide rises and falls in the same pattern.
A six-hour tide is expected to rise or fall in the 1st hour 1/12 of its range.
In the 2nd hour 2/12 of its range.
In the 3rd and the 4th 3/12 of its range.
In the fifth hour 2/12 of its range and in the 6th hour 1/12 of its range.